This invention relates to a miticidal composition and method for controlling spider mites. More particularly, this invention relates to a miticidal composition comprising a water-soluble acidic high molecular weight polymer of a branched crosslinked polymer obtained from one or more olefinic unsaturated carboxylic acids as active ingredient for various spider mites.
Among mites parasitizing plants, the most harmful ones are spider mites which harm fruit trees such as mandarin oranges, oranges, lemons, grapefruits, apples, etc., strawberries, eggplants, vegetables, tea plants, cucumbers and melons, etc., and woods. Further, since spider mites have a plurality of generations in one year and resistance to various synthetic miticides is found at an early stage commercially available miticides lose their practical control effects rapidly.
In order to solve such a problem there have been developed a solid paraffin emulsion and a emulsified machine oil, both exhibiting miticidal effective by physical action. But the former cannot prevent chemical injury, so that it is only used as spreader in small amounts. On the other hand, the latter is used mainly in the winter season when the metabolism of plants is lowered due to lower temperatures, in order to prevent chemical injury. It is also possible to purify a machine oil to give a spindle oil so as to lower the chemical injury. But it is well known that such an emulsified spindle oil cannot be used during the latter half of June to August, which period requires miticides most earnestly, in order to prevent the generation of oil stains, etiolation of leaves, latening of maturing of young fruits, degradation of quality of agricultural products such as fruits, caused by chemical injury. Particularly in the case of citrus fruits, since spraying of a machine oil emulsion before or after the spraying of N-(1,1,2,2-tetrachloroethylthio)-4-cyclohexene-1,2-dicarboxyimide (Difolatan), 2,3-dicyano-1,4-dithiaanthraquinone (Delan), or the like, which is a chemical for controlling scab disease, causes serious chemical injury such as leaf fall, the use of a machine oil emulsion is not allowable practically after the flowering period in an orchard sprayed with Difolatan, Delan, or the like.